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A cable-stayed bridge is a bridge that consists of one or more pillars located in the middle of the span, with cables supporting the roadbed. There are two major classes of cable-stayed bridges, differentiated by how the cables are connected to the pillars. In a parallel attachment design, the cables are made nearly parallel by having the height of attachment on the pillar be similar to the distance from the pillar along the roadway. In a radial attachment design, the cables all connect to or pass over the top of the pillar.

The cable-stay design occupies a sweet spot of length between cantilever bridges and suspension bridges. Within this sweet spot a suspension bridge would require more cable, while a full cantilever bridge would require considerably more material.

1 Comparison with suspension bridge

A multiple-pillar cable-stayed bridge may appear similar to a suspension bridge, but in fact is very different in principle and in the method of construction. In the suspension bridge, a large cable is is made up by "spinning" small diameter wires between two pillars, and at each end to anchorages into the ground or to a massive structure. These cables form the primary load-bearing structure for the bridge deck. Before the deck is installed, the cables are under tension from only their own weight. Smaller cables or rods are then suspended on the main cable, and used to support the load of the roadbed, which is lifted in sections and attached to the suspender cables. As this is done the tension in the cables increases, as they are also increased with the "live load" of vehicles or persons crossing the bridge. The tension on the cables must be transferred to the earth by the anchorages, which are sometimes difficult to construct due to poor soil conditions.

In the cable-stayed bridge, the pillars form the primary load-bearing structure. A cantilever approach is often used for support of the roadbed near the pillars, but areas further from them are supported by cables running directly to the pillars. This has the disadvantage, compared to the suspension bridge, that the cables pull to the sides as opposed to directly up, requiring the roadbed to be stronger to resist these loads; but has the advantage of not requiring firm anchorages to resist a horizontal pull as in the suspension bridge. All static horizontal forces are balanced so that the supporting pillar does not tend to tilt or slide, needing only to resist such forces from the "live" loads.

A further advantage of the cable-stayed bridge is that any number of pylons may be used. While it is possible to build a suspension bridge with one central tower, they are usually built with a pair of towers. Note that the apparent four-tower western segment of the San Francisco-Oakland Bay Bridge is in fact a pair of two-tower suspension bridges with a massive central anchorage.

2 Examples of cable-stayed bridges

• The Hangzhou Bay Bridge - spanning Hangzhou Bay , off the east coast of China, between Jiaxing and Cixi . When completed, it will be the longest cable-stayed bridge in the world.
• The East End Bridge - spanning the Ohio River between Proctorville, Ohio and Huntington, West Virginia
• The Millau viaductThe Millau Viaduct is a cable-stayed bridge that stretches across the Tarn river valley near Millau in southern France. It forms the last link in autoroute 75. With one pillar's summit at 341 m higher than the Eiffel tower it is the highest bridge in the - spanning the TarnDepartement deu Tarn Details Information Number81 Region Midi-Pyrenees Prefecture Albi Subprefecture Castres Population Total 1999 Density Ranked 65th 343,402 60 /km² Area5,758 km² Arrondissements 2 Cantons 46 Communes 324 President of the general council river near the town of MillauMillau (12100) is a city in Aveyron, Midi-Pyrenees, France La Graufesenque 2 km from Millau was the largest production centre of ceramics at the Gallo-Roman period. the Millau viaduct the Millau viaduct Tourism the glove museum micropolis; the city of ins in FranceThe French Republic or France ( French: Republique francaise or France is a country whose metropolitan territory is located in western Europe, and which is further made up of a collection of overseas islands and territories located in other continents., under construction. When completed, it will be the tallest bridge in the world.
• The Rio-Antirio bridgeThe Rio-Antirio bridge ( Greek: is a cable-stayed bridge linking the cities of Rio (near Patra on the Peloponnese) and Antirio on the western mainland Greece, thus connecting with the rest of Europe. The recently opened bridge will dramatically improve ac - spanning the Gulf of CorinthThe Gulf of Corinth is the body of water separating Peloponnese from western mainland Greece. It is bounded in the east by the Isthmus of Corinth, and in the west by the strait of Rio-Antirio, crossed by the Rio-Antirio bridge. It is almost surrounded by near PatraPatra (Greek: Modern: , Ancient: , Patrai is the third largest city of Greece, and also the capital of the Achaea region of Greece. Patra, or Patras, is located in the southwest part of Greece in Peloponnesos. It is also the seat of the Province of Patra., GreeceGreece formally called the Hellenic Republic (in Greek: ) Hellenike Demokratia , is a country in the southeast of Europe on the southern tip of the Balkan peninsula. It is bounded on land by Bulgaria, the Former Yugoslav Republic of Macedonia and Albania, the bridge with the longest cable-stayed section, a road bridge with four cable-stay pillars.

• The Pont de Normandie - spanning River Seine between Honfleur and Le Havre, northern France
• Queen Elizabeth II Bridge - spanning River Thames at Dartford Crossing, Kent
• Second Severn Crossing - River Severn estuary between England and Wales
• Dee River Crossing (Pont Sur Y Fflint) - near Shotton, north Wales (largest asymmetric cable-stayed crossing in UK)
• Delaware 1 - spanning the Chesapeake and Delaware Canal near St. Georges, Delaware
• Zakim Bunker Hill Bridge - spanning Charles River in Boston, Massachusetts
• Dames Point Bridge - spanning the St. Johns River in Jacksonville, Florida
• Sunshine Skyway Bridge - spanning Tampa Bay between Saint Petersburg, Florida and Bradenton, Florida
• The Oresund Bridge - spanning Oresund between Denmark and Sweden
• The Lune Millennium Bridge - a footbridge spanning the River Lune in Lancaster, England
• Fred Hartman Bridge - spanning the Houston Ship Channel between Baytown, Texas and La Porte, Texas.
• The Alex Fraser Bridge - spanning the Fraser River between Delta and Richmond in British Columbia, Canada
• Sundial Bridge - A single spar pedestrian bridge spanning the Sacramento River in Redding, California
• The West Gate Bridge - spanning the Yarra River in Melbourne, Victoria, Australia
• The Clark Bridge - spanning the Mississippi River in Alton, Illinois
• The Vasco da Gama Bridge crosses the estuary of the Tagus river in its wide part, at the North end of the city of Lisbon, Portugal.